1. Field of the Invention
The present invention relates to a method of preparing sodium formyl acetone and 4,4-dimethoxy-2-butanone. Each of sodium formyl acetone, which has ketone and aldehyde group in the molecule, and 4,4-dimethoxy-2-butanone, which is obtained by neutralizing and acetalizing sodium formyl acetone, is useful as a raw material in the synthesis of organic materials such as medicines and agricultural chemicals.
2. Description of the Related Art
A method of preparing sodium formyl acetone using as raw materials acetone, methyl formate and sodium methoxide is described in U.S. Pat. No. 2,760,985. In this method, a powdery sodium methoxide is used as a raw material. It should be noted that a powdery sodium methoxide tends to react with oxygen and tends to be decomposed by the moisture within the air. It follows that the loss of sodium methoxide, which is costly, leads to a high preparing cost of sodium formyl acetone. What should also be noted is that sodium methoxide, if attached to the human skin, causes scalding or the like, making it troublesome to handle a powdery sodium methoxide. Further, sodium methoxide in the reacting stage is in the form of a slurry having a very high viscosity, with the result that the mixing of the slurry for achieving a sufficient reaction within a reaction vessel is made difficult in the industrial production of sodium formyl acetone.
A method of preparing 4,4-dimethoxy-2-butanone by neutralizing and acetalizing sodium formyl acetone is also disclosed in U.S. Pat. No. 2,760,985. In this method, sodium formyl acetone is isolated as a solid material and, then, dissolved again in methanol when used in the preparation of 4,4-dimethoxy-2-butanone. It should be noted that a solid sodium formyl acetone is deliquescent, making it troublesome to handle the solid sodium formyl acetone. Further, use of a solid material is low in productivity in unit operation of separation, feeding, transportation, mixing, etc., compared with use of a liquid material. Thus, it is not desirable to use a solid material in the industrial production of 4,4-dimethoxy-2-butanone. What should also be noted is that hydrochloric acid is used in this method as a neutralizing and acetalizing reagent. Naturally, it is necessary to use an apparatus formed of a material selected in view of resistance to corrosion caused by chlorine, leading to a high equipment cost.
As described above, a solid sodium methoxide is used in the conventional method of preparing sodium formyl acetone using as raw materials acetone, methyl formate and sodium methoxide. The solid phase catalytic reaction employed in the conventional method is poor in reproducibility and necessitates troublesome operations, compared with a liquid-liquid reaction. In addition, the conventional method, when employed in the industrial production of sodium formyl acetone, is not sufficiently high in yield.
The conventional method of preparing 4,4-dimethoxy-2-butanone by neutralizing and acetalizing sodium formyl acetone also leaves much room for further improvement when the method is employed for the industrial production of 4,4-dimethoxy-2-butanone. For example, the conventional method is unsatisfactory in operability and necessitates an apparatus formed of special materials.
An object of the present invention is to provide a method of industrially producing sodium formyl acetone of high purity with a high yield using acetone, methyl formate and sodium methoxide as raw materials. For improving industrial operability, a liquid-liquid reaction is employed in the method of the present invention so as to simplify the industrial producing process.
Another object is to provide a method of industrially producing 4,4-dimethoxy-2-butanone with a high yield from sodium formyl acetone. The method of the present invention permits overcoming the above-noted problems inherent in the prior art.